The present invention relates to an organic electroluminescent element, and an electronic device provided with the organic electroluminescent element.
1. Field of the Invention:
An organic electroluminescent element (hereinafter, also referred to as organic EL element) has a configuration in which a light-emitting layer containing a light-emitting compound is sandwiched by an anode and a cathode. In addition, the organic EL element is a light-emitting element which utilizes a phenomenon of recombining, by applying an electric field, a positive hole injected from an anode and an electron injected from a cathode in a light-emitting layer to thereby produce an exciton, and a phenomenon of light emission (fluorescence, phosphorescence) in deactivating the exciton. The organic EL element is a whole solid element constituted of a film of an organic material having a thickness of just a sub-micron meter between the electrodes, and the light emission can be promoted by applying several volts to several tens of volts. Therefore, the application to the next generation flat displays or lighting devices is expected.
For example, as the organic EL element, there has been proposed to construct a white light-emitting element by laminating light-emitting layers which emit different lights such as red, green and blue (for example, refer to Patent Document 1, Patent Document 2, Patent Document 3)
However, the organic EL element has, principally a different light-emitting wavelength for each light-emitting color, and a different light-emitting energy for each light-emitting color. Therefore, there is a difference in decomposition of the organic material generated simultaneously with the light emission, and in deterioration rate of the element caused by the decomposition of the organic material.
Accordingly, in the organic EL element having the configuration of combining different light-emitting colors, there has occurred principally color shift with the lapse of time. Particularly, the life time of blue light having a high energy is apt to be shorter than red light and green light.
2. Description of the Related Art:
[Patent Document 1] JP 2008-218320 A
[Patent Document 2] JP 2007-173584 A
[Patent Document 3] JP 2003-151769 A
The organic EL element having the configuration of combining different light-emitting colors has, principally a different light-emitting wavelength for each light-emitting color, and a different light-emitting energy depending on each light-emitting color. Therefore, there is a difference in decomposition of the organic material generated simultaneously with the light emission, and in deterioration rate of the element caused by the decomposition of the organic material.
Accordingly, in the organic EL element having the configuration of combining different light-emitting colors, there has occurred principally color shift with the lapse of time. In addition, the color tone of the emitting lights of the organic electroluminescent element changes from the initial color tone with the lapse of time. As a result, the display quality of the organic electroluminescent element is lowered with the lapse of time.
In order to solve the above-described problem, the present invention is to provide an organic electroluminescent element capable of suppressing the lowering of the display quality, and an electronic device.